Stretchable tubular knit fabric of yarn coated with elastomer



June 7, 1966 M. STORTI I 3,255,030

STRETCHABLE TUBULAR KNIT FABRIC OF YARN COATED WITH ELASTOMER Filed Feb.12, 1963 Michael Sforfi physical properties of the fibers themselves.

United States Patent 3,255,030 STRETCHABLE TUBULAR KNIT FABRIC OF YARNCDATED WITH ELASTOMER Michael Storti, Barrington, 12.1., assignor toRohm & Haas Company, Philadelphia, Pa, a corporation of Delaware FiledFeb. 12, 1963, Ser. No. 258,003 1 Claim. (Cl. 1177) The presentinvention relates to a novel and useful elastomer-impregnated fabricsuitable for garment use, to a process for producing such a fabric, andto a process for adapting such fabric to a finished garment. Moreparticularly, it relates to a fabric equally stretchable in bothdimensions and characterized by exceptional modulus which may be made onconventional weaving and/or knitting machinery.

Broadly considered, an elastic fabric is any fabric capable ofrecovering size and shape after deformation. Thus, technicallyconsidered, knit fabrics and fabrics woven or knit with textured yarnmay be considered to be elastic. However, the industry has furtherdefined the term elastic so that fabrics are considered elastic only ifthey also possess power (i.e., modulus) and speed of recovery.

In the standard shuttle weave, the resulting fabric has no elasticityexcept insofar as is imparted thereto by the If the individual threadshave no elasticity, neither does the resulting cloth.

The conventional method for producing an elastic fabric (i.e., onepossessing not only the ability of recovering size and shape afterdeformation but also including power and high speed recovery) is toweave or knit an elastomeric thread of natural rubber or of a syntheticelastomer with a hard, nonstretch thread. To provide the appearance,dyeability and hand desired in the finished product, it is conventionalto cover the elastomeric thread with a hard fiber such as cotton, rayon,etc. In covering the elastic thread, the fiber is fed vertically in amachine of special design and as it travels in the perpendicular, thehard fibers are spiraled around the elastic thread. Normally, there aretwo stations for covering, with one covering fiber traveling in aclockwise direction and the next fiber traveling in a counterclockwisedirection. The speed at which the elastomeric thread travels and thespeed of the covering fiber are varied to obtain specificcharacteristics of modulus and ultimate elongation. These coveredelastic threads are then woven and/or knit with hard threads to producean elastic fabric. The tension applied to the elastic thread in theweaving or knitting process again affects the characteristics of modulusand elongation of the finished fabric. Size and physical characteristicsof the elastomeric threads must be carefully chosen to obtain specifiedresults in the finished fabric. All phases of the manufacture of anelastic fabric are critical to the finished quality. Restrictionsimposed by the Weaving process and high speed textile machinery limitthe use of elastic threads in shuttle weave cloth to its presence in thewarp only. The industry has long sought to produce textiles possessingboth 7 stretchability and modulus.

Prior to the existence of elastic fibers, stretchability was imparted tostandard fibers, such as cotton, wool, etc., by a particular weave knownas a knit weave. The basic knit weave, termed the circular weave,produces only tubular goods. Circular Weave imparts stretchability tothe resulting fabric, but with little accompanying modulus, i.e., theforce returning the fabric to its original dimension when stretched isvery low. More recently, machinery has been devised that produces fiatcloth with a knit structure, thus obtaining a fiat fabric havingstretchability. The advantage of the resulting fiat textile is obvious,in that it permits cutting and shaping the fabric to precise garmentneeds. In the tricot knit, the knit goods produced are fiat but havestretchability in only one dimension. The rachel knit also produces aflat, knitted fabric but possessing stretchability in two dimensions.However, the stretchability in the one dimension is significantly betterthan in the other. The kidde knit produces a flat cloth having equalstretchability in both dimensions. Thus, by means of various knitweaves, it is possible to impart stretchability but not modulus to atextile. The knit weaves, particularly those designed to produce a flatfabric, are expensive to produce, primarily because of the costlystart-up times after a break. It is possible to impart modulus to aknitted fabric by using an elastic thread for all or part of the fabric.The necessity of running the machines at just below the break point ofthe fabric leads to difiicult mechanical problems and to costly start-uptime and other expenses due to the frequent breaks which result fromusing this type of fiber under these conditions (any elastic fiber hassignificantly reduced tensile strength at maximum elongation as comparedto its tensile strength at normal elongation), i.e.,

textile machinery is operated just below the break point of the fiberused.

There have recently been developed a number of processes for texturing ayarn whereby considerable extensibility is imparted to the yarn. Suchprocesses are applicable to any of the basic yarn forms asmulti-filament, spun staple or plied yarn with resulting yarn beingtermed a stretch yarn. The processes for producing stretch yarns aregenerally divided into two major classifications: the nontorque andtorque processes. In general, nontorque processes involve crimping theyarn as by passing the yarn over a heated edge, through a stutfer box,etc. Commercial processes utilizing such means include Agilon, Ban-Lon,etc. The torque processes involve twisting the yarn to produce thedesired degree of deformation. Different processes involving diiferentcombinations of heat setting and twisting have been developed, includingthe monofil process, the false twist process, and many variations ofthese basic processes. The most commonly used torque process is knownunder the tradename Telanca and is described, for example in US.2,564,245. At the present time, such stretch yarns are generallyconfined to thermoplastic fibers. However, this limitation is notinherent and stretch yarns may be made from wool, cotton, etc., asdescribed for example, by Finlayson et al. in US. 2,089,198. In general,any yarn which may be set in a compacted condition such that the set ispermanent to any chemical or physical action that the yarn willencounter in its normal life can be made into a satisfactory stretchyarn.

By means of these various processes, considerable stretchability may beimparted to the resulting yarns. Further, when such a yarn is subjectedto tension in a standard textile making machinery, there is no loss instrength in the fiber in contrast to elastic fibers which haveconsiderably reduced strength under tension and thus are subject tobreaks and costly start-up time delays. This results from the fact thatthe tensile strength of the textured yarn far exceeds the strength ofany of the elastomeric yarns. Consequently, there is greatly reducedbreakage during the knitting process which permits higher knittingspeeds. This results in considerably lower knitting costs. However, thetextiles produced using stretch yarns, while displaying considerableextensibility, have very little modulus.

Accordingly, it is an object of the present invention to impart a highdegree of modulus to a fabric whether woven in a standard shuttle weaveor any of the knit weaves.

Another object of the invention is to produce an elastic fabricpossessing a high modulus and high speed of recovery without the use ofelastic fibers.

A further object of the invention is to prouce an elastic fabricpossessing high modulus and high speed of recovery using textured yarnsprepared from hard fibers.

It is another object of the invention to produce an elastic fabricpossessing high modulus, utilizing standard commercial knitting and/ orWeaving machinery.

Again, an object of the invention is to produce finished garments havingcontrolled modulus varying across the garment by a simple mouldingprocess, i.e., substantially free of seams.

Again, it is an object of the invention to produce a fabric having highmodulus with substantially unimpaired breathability, permeability anddyeability.

Still another object is to produce a high strength elastic fabricpossessing good counter appeal.

Another object of the invention is to produce an elastic fabric havingexcellent durability.

A further object of the invention is to produce a fabric from spunstaple yarn whichdoes not pill.

These and other objects of the invention Will become apparent in thefollowing description of the invention.

These objects are accomplished by the present invention which provides afabric having high modulus with high durability, excellent counterappeal, and with unimpaired dyeability and permeability, by thoroughlyimpregnating a fabric prepared from a stretch yarn with a normally tackysettable elastomer While the fabric is in its relaxed state, controllingthe degree of impregnation of the fabric so that only the individualyarns of the fabric are coated stretch yarn in only the Warp or the weftin which case modulus and speed of recovery are imparted to the stretchyarn giving a one-way stretch fabric. It is preferred to use amultifilament yarn prepared from continuous filaments. When such a yarnis impregnated and cured according to the invention, even the smallindividual impregnated filaments act as elastic members by pulling thefabric to its original shape upon release of tension.

Any process for texturing the yarn to impart stretchability thereto 'maybe used, including both torque and nontorque processes. Any standardweave or knit may be used in making the textile, including shuttleweave, leno weave, circular knit, tricot knit, rachel knit, kidde knit,etc. The stretch yarns may be prepared from any type of fiber, includingnatural fibers such as cotton, wool, linen and the like, and syntheticfibers such as the nylons, polyesters, polyacrylonitriles, polyvinylalcohol, polyureas, polyurethanes, cellulose esters and other such knownmaterials. It is preferred to employ nylon, i.e., poly(hexamethyleneadipamide), both by reason of the commercial availability of stretchnylon yarns and the high inherent strength of such stretch nylon yarns.

The invention is illustrated in the figures wherein FIG. 1 is aphotomicrograph of a knit fabric prepared from a texturized nylon yarn(Helanca) which has not been impregnated, and FIG. 2 is aphotomicrograph of a knit fabric prepared from a texturized nylon yarn(Helanca) impregnated with an elastomeric polyurethane resininaccordance with the instant invention.

As can be seen from FIG. 2, the individual yarn fibers retain theirdistinct identity when treated in accordance 4 with the instantinvention, thereby imparting permeability and breathability to theresulting fabric.

The precise process for impregnating the yarn fabric in accordance withthe instant invention is not critical and will vary, depending on theelastomeric material employed and the nature of the product to beproduced. Thus, the textile may be impregnated by immersion, spraying,roller coating, continuous dipping, etc. Certain of these processes,such as spraying, may be adapted on a continuous basis as to control thedegree of saturation of the textile and thus eliminate the necessity forany subsequent step to remove any undesired excess of impregnatingelastomeric material.

The advantages of the instant process are many. Thus it is extremelydifficult to impregnate and cure a single textured yarn in its relaxedstate. However, the present process which impregnates the yarn when madeup into a fabric is simple, easily automated, and much less costly. Inaddition to the greater ease, practicability and lower cost of theimpregnating and curing steps themselves, it is also much less expensiveto knit or weave a fabric with a textured yarn than a fabric containingelastic yarns. Whereas only a portion of the yarns of present elasticfabrics are themselves elastic, in the fabrics produced by the instantinvention, each texturized yarn becomes an elastic yarn.v In addition,the amount of modulus and speed of recovery may be easily regulatedby-controlling the degree of impregnation, the nature of the elastomerused, the amount of tension applied during curing, etc. Further, manynovel effects can beobtained in knitting and weaving without elasticyarns. Moreover, fabrics can be produced from stretch yarns on standardweaving and knitting equipment, whereas such equipment requiresmodifications to handle elastic yarns and then only at a considerablylower production rate. The cost of producing an elastic fabric is, thus,reduced substantially and the style, hand and design of the finishedfabrics will be limited only by the limitations of the knitting andweaving machinery. The instant process which permits the use of texturedyarns to the exclusion of elastic yarns is thus a significantimprovement in this regard,

A particularly preferred embodiment of the invention is to mold theimpregnated fabric just prior to the curing step into a desired shape orform and then cure the impregnated fabric on the mold. The elastomericmaterial employed not only imparts modulus to the resulting curedtextile but also permanent set. In addition, the degree of modulus inthe fabric varies inversely with the degree of stretching in the moldingoperation, thus permitting imparting variable modulus to the fabricwithout any cutting or shaping being necessary.

Such properties in the resulting product render the process particularlyapplicable in the production of various womens garments and other useswherein such properties are desirable. For example, in producing aswimming suit, a circular knit stretch nylon tube of a circumferencedesired for the particular size to be produced is immersed in anelastomeric solution, rolled flat to remove the excess impregnatingsolution, and the tube then placed on a form simulating the femalefigure. The wet impregnated tube will conform faithfully to the mold.The form is then cured in a circulating air oven and, after curing iscompleted, the form is removed from the oven and the cured impregnatedstretch nylon tube is removed from the form. The resulting nylon tubenow has the exact shape of the original model and needs only the top andbottom selvage edges to become a finished bathing suit. Further, withthe exception of such edges, there are no bulky scams or stitches in thegarment. -In addition, the suit will have excellent modulus which, inturn, will vary across the suit; the hip areas having less modulus andthe stomach areas having a greater degree of modulus as is desirable inthis type of product.

Any elastomeric material which is soluble or dispersible in a liquidcarrier and is settable to a resilient, tack-free elastomer may be usedfor impregnating the fabric. Such elastomers include, withoutlimitation, those prepared from acrylates, natural rubber,styrene-butadiene, butadiene-acrylonitrile, butyl rubber,ethylene-propylene rubber, chlorosulfonated polyethylene, polyesterelastomers, cis-polyisoprene, fluorocarbon rubbers, polyester-polyamideelastomers, cis-polybutadiene, chloroprene rubber, urethane elastomersprepared from either polyethers or polyesters, etc. It is preferred touse a polyurethane prepared from either a polyester-diisocyanate or apolyether-diisocyanate. The terms polyester-diisocyanate andpolyether-diisocyanate indicate a polymer which contains relatively lowmolecular weight polyester or polyether chains which are capped orextended by diisocyanates to give a prepolymer containing urethanelinkages and free isocyanate groups which can be cured by difunctionalor polyfunctional compounds containing active hydrogen radicals, such aswater, dithiols, etc., as disclosed, for example, by Kirschner in U.S.patent application Serial No. 237,350, filed November 13, 1962. Theresulting cured segmented polyurethane is of relatively high molecularWeight, being close to or exceeding the molecular weight required forfilm-forming properties.

The polyesters suitable for use in preparing the polyester-diisocyanateprepolymers useful in the present invention are of relatively lowmolecular weight, having a molecular weight below that which is requiredfor filament formation. In general, the suitable polyesters have amolecular weight of from about 1,500 to about 5,000 and are liquid orhave a low melting point generally not substantially in excess of 100 C.The polyesters are formed from glycols and dicarboxylic acids oresterforming derivatives thereof by a simple condensation reaction, andthe resulting products are primarily linear, although small amounts ofcross-linking agents, such as tricarboxylic acids, glycerol orunsaturated acids, may be used to produce a variation in the finalproduct. Saturated aliphatic dicarboxylic acids, such as adipic,succinic, glutaric, pimelic, suberic, azelaic, sebacic, malonic and thelike, may be employed with aliphatic glycols, such as ethylene glycol,diethylene glycol, triethylene glycol, decamethylene glycol and1,12-octadecanediol. Aromatic acids, such as isophthalic,p-phenylenediacetic acid, etc., and alicyclic acids, such ashexahydroterephthalic acid, may likewise be used. An excess of theglycol is used so that the polyester has terminal alcoholic hydroxylgroups. The polymerization may be carried out without catalysts, or, ifdesired, known esterification catalysts, such as dibutyl-tin-dilaurateor tin octoate, may be used to hasten the reaction.

As an alternative to the polyesters or in conjunction therewith, theremay be used one or more polyethers. Such polyethers are anhydrouschain-extended polyethers having ethereal oxygen atoms separated byhydrocarbon chains either aliphatic or aryl in nature. The ether shouldalso contain terminal groups reactive to isocyanate, such as alcoholichydroxyl groups. Such materials are gen erally linear in structure butmay be branched somewhat. For example, typical polyols includepentanediol-l,5; 2-

ethylpropanediol-lfi; 2-methylpropanediol-1,3; hexanediol;3,4-dihydroxycyclopentane and its polyethers; xylene- -alpha, alphadiols; trimethylolpropanes; hexenetriols and triols with polypropyleneor ethylene chains; etc. The preferred ethers contain the structureH(OR),,OH, wherein R is a hydrocarbon radical and n is an integersufficiently high to give a molecular weight of preferably from about500 to about 5,000. Such ethers are prepared by condensing an alkyleneoxide, such as ethylene oxide or propylene oxide or a mixture thereof,with each other or other alkylene oxides, such as styrene oxide, etc.Condensation products may also be prepared by condensing such alkyleneoxides with diols, triols, etc., such as those disclosed above.

Further examples of suitable polyesters and polyethers for use as thepolyol in preparing polyurethanes are described in U.S. Patents2,814,606; 2,801,990; 2,801,648;

2,777,831; 2,606,162, and 2,432,148. These patents also teach the methodof preparing such polyols.

Where the elastomer used in the impregnating step of the presentinvention is a polyurethane, it is understood that the polyurethane willbe in the form of a suitable prepolymer containing free isocyanategroups. Because of the presence of the reactive isocyanate groups, thepolyurethane will necessarily be applied to the fabric as a solution ordispersion in an inert organic solvent. The diisocyanates used inpreparing the prepolymers are those customarily used in the polyurethaneart, such as the toluene diisocyanates (particularly the -20 mixture of2,4- and 2,6-toluene diisocyanate), the naphthalene diisocyanates,p,p'-diphenylmethane diisocyanate, p-methane diisocyanate, and the like.A more complete list of polyisocyanates is set forth by Siefken inAnnalen, volume 562, pages 122-135 (1949).

The prepolymer is formed by reacting the polyester or polyether with thediisocyanate under anhydrous conditions at a slightly elevatedtemperature. In general, a temperature of from about 50 C. to about C.is employed, although temperatures somewhat lower can be used with anundesirable increase in reaction time. When employing a temperaturewithin the range of 50 C. to 150 C., a reaction time of about 5 to 60minutes is generally required, with the lower temperatures requiring thelonger time interval. The preparation of the prepolymer is not criticalfor the present invention, and any method known to those skilled in theart may be used therefor.

Upon the formation of the prepolymer, it is dissolved in an inertorganic solvent. The concentration of prepolymer in the solvent is notcriticalso long as the viscosity of the solution is low enough to permitready absorption by the textured yarns and not so high as to supportitself in forming a film between the yarns. In general, theconcentration will vary with the nature of the prepolymer and thesolvent, the method of application to the textile, the type ofafter-treatment necessary to remove excess elastomer, the efficiency ofthe solvent recovery process, etc. Generally, such solutions containfrom about 5 to about 50% prepolymer based on the weight of thesolution. A relatively inexpensive inert and satisfactory solvent forthe prepolymer is 1,1,1-trichloroethane, which boils at about 74 C.,although other volatile solvents, such as carbon tetrachloride,chloroform, other halogenated hydrocarbons, ethers, aromatichydrocarbons, etc., may likewise be used. 'A small amount of water,dithiol and/ or othercuring agent may be emulsified or dispersed in theprepolymer solution used to impregnate the fabric or, alternatively, thecuring agent may be separately applied in liquid and/or vapor form afterthe fabric has been impregnated.

The use of other elastomeric materials is less critical than thepolyurethanes, due to the relative absence of highly reactive groups inthe elastomer. Accordingly, such elastomers may be applied as solutions,emulsions, or dispersions from either organic liquid carriers or fromwater. By reason of the ease of handling, lack of toxicity, cheapnessand absence of solvent recovery steps, it is preferred to use anemulsion or tacky dispersion of the elastomer in Water for impregnatingthe textile with such elastomers. Again, it is important that theviscosity of the impregnating solution or dispersion or emulsion be lowenough to permit ready absorption by the textured yarns and not so highas to support itself in forming a film between the yarns.

After impregnation, the fabric may be immediately cured or, if an excessof elastomer has been picked up by the fabric, the excess is expressedfrom the fabric by any suitable means, such as squeezing, etc., prior tothe curing treatment. The time and temperature of curing will vary withthe nature of the elastomer and of the liquid carrier for'the elastomer.Generally, for any particular Z elastomer-liquid combination, the higherthe temperature, the shorter the time of curing. In general, atemperature within the range of from about 50 C. to about 250 C. isemployed, although ambient temperature can be used if time is notimportant. At temperatures of from about 50 C. to 250 C., the liquidcarrier readily evaporates and curing is generally accomplished withinan hour and frequently within minutes. If desired, a partial cure may beeffected by heating, and the final curing completed at room temperature.Where an organic solvent is used, it is preferred that at least someheating be carried out to evaporate the solvent so that it can becondensed for recovery purposes.

While the process is described herein as a batch process, it isadaptable to be run on a continuous basis, using apparatus already knownfor impregnating fabrics. Thus, in many instances, a change in themachinery currently employed is not even necessary to convert to thepresent process. For example, the molding and curing process asdescribed herein may be carried out on a conventional Tubetex equipmentif desired.

The following examples are given to illustrate the invention and are notintended to limit it in any way. All parts are by weight unlessotherwise so stated.

Example 1 An aqueous dispersion containing 45% of an emulsion copolymerof about 0.8% of acrylamide, 98% of ethyl acrylate, and 1.2% ofN-methylolacrylamide was prepared by emulsion copolymerization. Theemulsion may be used to impregnate a texturized rayon.

As applied to a textile prepared from spun staple rayon, 2-denier,1.5-inch length, and weighing about 0.5 ounce per square yard, thefabric was padded through the polymer dispersion to provide a 125% wetpickup. After airdrying, the treated web was heated at 300 F. for fiveminutes. The resulting bonded web was quite flexible and soft andwithstood laundering in an automatic washer employing A cup of acommercial laundry detergent (available under the trade name Tide) in 15gallons of water at 140 F. The fabric also withstood dry-cleaning in acleaning fluid formed of three gallons of carbon tetrachloride, oneounce of water, and 4.5 grams of the sodium salt of dicaprylsulfosuccinate. The dry-cleaning was effected in a portableagitator-type washer for a period of 30 minutes;

The bonded fabric was also bleached and scorched according to the AATCCtest fordamage caused by rerained chlorine (69-1958). No discolorationof the fabric occurred as a result of this treatment.

Example 2 A solution is prepared of four parts of sodium lau ryl sulfatein 100 parts of water. A mixture of 32 parts of ethyl acrylate and 59.5parts of vinylidene chloride is added with stirring to the solution. Theresulting mixture is cooled to 18 C. A solution of 02 part of ammoniumpersulfate in three parts of water is then added, followed by theaddition of 0.25 part of sodium hydrosulfite in three parts of water.Stirring is continued throughout the reaction. In a short time, thetemperature of the mixture begins to rise and continues to rise to 40C., where it is maintained with the aid of an ice bath. At the end ofthe reaction, the product is cooled to 18 C. It is then adjusted to a pHof 9.5 with ammonium hydroxide. The testing of the latex is shown inExample 4.

Example 3 A solution is prepared of 3.5 parts of the sodium salt ofdioctyl sulfosuccinic acid in 150 parts of water. A mixture of 32 partsof ethyl acrylate and 33.9 parts of vinylidene chloride is addedwithstirring to the solution. The resulting mixture is then cooled to 17 C.A solution of 0.15 part of ammonium persulfate in two parts of water isthen added, followed by the addition of 0.2 part of sodium hydrosulfitein four parts of water. Stirring is continued throughout the reaction.In a short time, the temperature of the mixture begins to rise andcontinues to rise to 40 C., where it is maintained with the aid of anice bath. At the end of the exothermic reaction, thereaction mixture iscooled to 25 C. and 32 parts of vinylidene chloride are slowly added tothe reaction mixture over a period of 25 minutes to effect grafting ofthis latter portion of vinylidene chloride on to the initially-formedcopolymer. At the end of this time, 0.1 part of ammonium persulfate intwo parts of water and 0.12 part of sodium metabisulfate in three partsof water are added to the reaction mixture. At the completion of thereaction, the pH is adjusted to 8.5 with triethylamine. The testing ofthe material is shown in Example 4.

Example 4 To about 143 gms. ofan aqueous latex of natural rubbercontaining 70% rubber solids are added 0.5 gm. KOH, 1 gm. sodium dioctylsuccinate, 1.6 gm. 2,2-methylene-bis (4-ethyl, 6-tertiary butylphenol)as an antioxidant, 0.26 gm. B2180 0.18 gm. butyl Zimate, 0.83 gm.zinc-Z-mercaptobenzothiazole, 1.7 gm. of sulfur, 3 gm. zinc oxide, and0.1 gm. sodium sulfide. After thorough mixing, the latex was dilutedwith H O to give 60% solids.

The latices of Examples 2-4 are each applied to a stretch nylon fabric(Helanca), and the impregnated fabrics are lightly squeezed to removeany excess elastomer. The impregnated fabrics are cured in a circulatingair oven for 15 minutes, care being taken to maintain the fabric in analmost completely relaxed state during both immersion and cure. Theresulting fabric has both increased crispness and stretch, as well asexcellent modulus in all directions. Further, the resulting textiles arecompletely permeable and without significant alternation in theirphysical appearance from their appearance prior to impregnation.

I Example 5 A prepolymer was prepared using a commercial polyesterhaving the trade name D6 (Rubber Corporation of America). The polyesterhas a molecular weight of about 3,700, an acid number of about 0.8, ahydroxyl number of about 35, and contains less than 0.1% water. Theglycol used to prepare the polyester is a mixture of about ethyleneglycol, about isopropylene glycol, and a small amount of triol. Thepolyester is degassed for two hours at C. to C. and 10 mm. of mercurypressure. To parts of this polyester are added about 15 parts oftolylene diisocyanate, an 80 20 mixture of 2,4- and 2,6-tolylenediisocyanate and about 0.5 part of a tin catalyst (dibutyl tindilaurate). The mixture is reacted for one hour, while maintaining thetemperature at 80 C. to 90 C. to give a prepolymer having about 4% freeNCO content. Then, while maintained under a nitrogen blanket, there arestirred in at 80 C. five parts of toluene containing 0.5 part of acommercial ultraviolet absorber (the product tradenamed Tinuvin P isused), and 0.1 part of a blue dye (trade name Solfast Blue), followed by590 parts of'1,1,1-trichloroethane. After solution is complete, 7.9parts of water are emulsified into the solution. A stretch nylon fabric(Helanca) is then immersed in this solution for ten seconds, removed,squeezed lightly to remove excess solution, and cured in a circulatingair oven at about C. for 12 minutes, the fabric being maintained in arelaxed state during immersion and cure. There is obtained a textilewherein each individual fiber of the textile is an elastic fiberpossessing excellent modulus. Moreover, when the fabric is stretched tomaximum elongation, there is no loss in strength at such maximumelongation. The fabric is completely breathable and is not appreciablychanged in physical appearance from its appearance prior toimpregnation.

If desired, the pickup of the elastomer from the emulsions ordispersions may be improved in some cases by the use of a cationicagent, preferably as the emulsifier or dispersing agent. These and othermodifications of the process will be apparent to those skilled in theart.

By carrying out the impregnating and curing steps on the textile ratherthan on the separate yarns prior to weaving and knitting, the problem ofmaintaining the stretch yarns in a relaxed condition during suchtreatment is tremendously simplified. Further, the instant inventionpermits the weaving or knitting steps to be carried out on the stretchyarn while the yarns are still in a nonelastic state, i.e., havinglittle modulus. This permits faster and easier operation of conventionaltextile machinery. While the impregnating and curing steps illustratedabove are carried out on the textile in a substantially relaxedcondition (i.e., only that tension necessary to control the continuousfeed of the fabric), it is understood that tension may be applied toselected portions of the impregnated'fabric, which tension is maintainedduring the curing operation to produce a product having variablemodulus. Such a process is exemplified above in the molding process forproducing a bathing suit. Thus, the process is applicable to textileswhich are either substantially relaxed or which have tension appliedonly to selected areas thereof.

What is claimed is:

vA garment possessing high modulus, the degree of modulus varying acrossthe garment, said garment being free from seams other than selvedgeedges, said garment comprising a tubular knit fabric prepared from astretch yarn, each yarn being coated with a thin elastomeric coatingconforming to the individual yarns, the interstices between said yarnsbeing unfilled by said coating to preserve substantially all of thenatural interstices between said yarns, said elastomer having been curedwhile varying tension is applied to the fabric comprising said garment.

References Cited by the Examiner UNITED STATES PATENTS 2,213,883 9/1940Lurie 161-89 2,335,321 11/1943 Szegvari et al. 117-47 2,434,111 1/1948Hawley 1177 XR 2,469,961 5/1949 Gottchalck et al. 2239 2,564,245 8/1951Billion 57157 2,677,872 5/1954 Teague.

2,699,396 1/1955 Francis 117-135.5 XR 2,703,887 3/ 1955 Kennedy.

2,993,813 7/1961 Tishbein 117138.8 XR 2,995,781 8/1961 Sipler 264-1373,070,870 1/ 1963 Alexander et al. 264324 X WILLIAM D. MARTIN, PrimaryExaminer. T. G. DAVIS, Examiner.

